179
FXUS66 KPQR 071140
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
440 AM PDT WED OCT 7 2026
UPDATED AVIATION DISCUSSION AND WATCHES/WARNINGS/ADVISORIES.
SYNOPSIS
UNSEASONABLY WARM AND DRY WEATHER WITH WEAK
OFFSHORE FLOW WILL PERSIST THROUGH THURSDAY, BEFORE A TROUGH
BRINGS A RETURN TO COOLER TEMPERATURES WITH CHANCES FOR LIGHT
RAIN FRIDAY INTO SATURDAY. COOL NIGHTS WILL BRING CHANCES FOR
MORNING FROST IN RURAL VALLEYS AWAY FROM URBAN CORES THIS
WEEKEND INTO EARLY NEXT WEEK.
SHORT TERM...NOW THROUGH THURSDAY NIGHT
BROAD UPPER-LEVEL
RIDGING CENTERED OVER THE WEST COAST WILL CONTINUE TO AMPLIFY
THROUGH THURSDAY, BRINGING A WARMING TREND WITH CONTINUED DRY
WEATHER. VERY WEAK THERMAL TROUGHING ALONG THE COAST WILL ONLY
SUPPORT A PRESSURE GRADIENT OF AROUND -1 MB BETWEEN PORTLAND AND
THE DALLES, WHICH IN TURN SUGGESTS OVERNIGHT OFFSHORE WINDS IN
THE CASCADES AND FOOTHILLS ONLY REACHES 10-15 MPH. AFTERNOON
HIGH TEMPERATURES WILL TREND UPWARD TO THE MID 70S TO LOW 80S
WITHIN INLAND VALLEYS ON THURSDAY, VALUES SOME 10 OR SO DEGREES
ABOVE NORMAL FOR EARLY OCTOBER. DAILY RECORDS ON THURSDAY AT
MOST CLIMATE SITES APPEAR TO BE OUT OF REACH WITH LESS THAN 5%
CHANCES OF TYING OR SURPASSING EXISTING RECORD VALUES, EXCEPT
FOR SLIGHTLY HIGHER CHANCES OF 5-10% AT SALEM AND EUGENE. SEE
THE CLIMATE SECTION BELOW FOR A FULL LIST OF RECORD TEMPERATURES
FOR OCTOBER 8.
AFOREMENTIONED LIGHT OFFSHORE FLOW AT NIGHT WILL SUPPORT DRY
MID-LEVELS, WHICH WILL ALLOW EFFICIENT RADIATIVE COOLING AND
MORNING LOW TEMPERATURES FALLING TO THE UPPER 40S TO LOW 50S.
WHILE NOT AS WIDESPREAD AS RECENT MORNINGS, SOME AREAS OF FOG OR
LOW CLOUDS MAY DEVELOP ALONG THE COAST OR IN SHELTERED VALLEYS.
BY THURSDAY NIGHT, HIGH CLOUD COVER WILL BEGIN TO INCREASE
AHEAD OF AN APPROACHING WEATHER SYSTEM. -36
LONG TERM...FRIDAY THROUGH TUESDAY
MODEL CONSENSUS HAS
CONTINUED TO INCREASE REGARDING THE EVOLUTION OF AN UPPER-LEVEL
TROUGH OVER THE GULF OF ALASKA. THE TROUGH, WITH A LEADING
SHORTWAVE IMPULSE, WILL MOVE INLAND OVER THE PACIFIC NORTHWEST
FROM THURSDAY NIGHT INTO FRIDAY, BRINGING AN INITIAL ROUND OF
LIGHT RAIN SHOWERS ASSOCIATED WITH A WEAK FRONT MOVING ONSHORE.
RAIN MAY BEGIN EARLY FRIDAY MORNING ALONG THE COAST, BUT WILL
MORE LIKELY HOLD OFF UNTIL THE LATE MORNING OR EARLY AFTERNOON,
THEN REACH INLAND TO THE I-5 CORRIDOR BY THE AFTERNOON TO EARLY
EVENING. THIS WILL FAVOR ACCUMULATIONS ALONG THE NORTH OREGON
AND SOUTH WASHINGTON COAST AS WELL AS IN THE CASCADES AND
WESTERN FOOTHILLS THROUGH THE DAY ON FRIDAY, WHILE AREAS ALONG
THE CENTRAL OREGON COAST AND WITHIN THE WILLAMETTE VALLEY MAY
TEND TO STAY DRY. MEAN FORECAST RAIN TOTALS DURING THIS PERIOD
ARE 0.1-0.15 INCHES NORTH OF TILLAMOOK HEAD AND IN THE MOUNT ST.
HELENS AREA, WITH LOWER AMOUNTS OF 0.05-0.1 INCHES ELSEWHERE IN
THE LOWER COLUMBIA AND COWLITZ VALLEYS, ALONG THE COAST FROM
TILLAMOOK HEAD TO LINCOLN CITY, AND IN THE NORTH OREGON AND
SOUTH WASHINGTON CASCADES. AS THE TROUGH MOVES INLAND, A SECOND
SHORTWAVE IMPULSE MOVING SOUTH ON ITS WESTERN FLANK ON SATURDAY
WILL SEE THE TROUGH ELONGATE AND EVENTUALLY PINCH OFF INTO A
CLOSED UPPER LOW WHICH WILL SETTLE SOUTH OVER CALIFORNIA BY
EARLY NEXT WEEK. THIS FEATURE WILL RESULT IN ANOTHER CHANCE FOR
LIGHT RAIN ON SATURDAY AFTERNOON, WITH MORE WIDESPREAD POTENTIAL
FOR UP TO 0.1 INCHES OF RAIN, ESPECIALLY TO THE NORTH OF US-20,
BEFORE TRENDING DRIER BY SATURDAY EVENING AND NIGHT. ALL TOLD,
THE CHANCES FOR 0.25 INCHES OF RAIN IN 48 HOURS REACH ONLY
30-50% IN THE WETTEST AREAS NORTH OF TILLAMOOK HEAD AND IN THE
CASCADES AT FOOTHILLS NORTH OF OR-22. ELSEWHERE, THOSE CHANCES
ARE 5-15% FROM LINCOLN CITY TO TILLAMOOK HEAD AND ALONG I-5
NORTH OF SALEM, AND 5% OR LESS SOUTH OF LINCOLN CITY AND SALEM.
AS THE INITIAL FRONT MOVES INLAND FRIDAY EVENING THOUGH FRIDAY
NIGHT, PEAK GUSTS OUT OF THE WEST IN THE CASCADES, COLUMBIA
RIVER GORGE, AND HOOD RIVER VALLEY COULD REACH 30-40 MPH. BEHIND
THE BOUNDARY AND AS THE CORE OF COOLER AIR ALOFT MOVES OVERHEAD,
TEMPERATURES WILL QUICKLY FALL BACK TOWARD SEASONAL NORMS IN THE
UPPER 50S AND 60S FRIDAY THROUGH THE WEEKEND. OVERNIGHT LOWS
WILL SIMILARLY TREND COOLER, ESPECIALLY SATURDAY AND SUNDAY
NIGHTS WHEN THERE ARE 70% OR GREATER CHANCES FOR FROST IN THE
UPPER HOOD RIVER VALLEY, AND 20-50% CHANCES IN CASCADE VALLEYS,
NORTH OREGON COAST RANGE VALLEYS, THE UPPER COWLITZ VALLEY, AND
THE WILLAMETTE VALLEY SOUTH OF SALEM. CHANCES FOR A TRUE FREEZE
ARE 40-60% IN THE UPPER HOOD RIVER VALLEY NEAR PARKDALE AND DEE,
AND 20-40% ALONG OR-58 BETWEEN EUGENE AND OAKRIDGE. THOSE WITH
AGRICULTURAL INTERESTS OR HOME GROWERS WITH SENSITIVE OUTDOOR
PLANTS SHOULD CONTINUE TO MONITOR THE FORECAST THIS WEEK.
BY EARLY NEXT WEEK AS THE CLOSED LOW DRIFTS TO THE SOUTH, UPPER
HEIGHTS MAY BRIEFLY RISE AS RIDGING REDEVELOPS OVERHEAD. THIS
WILL FAVOR A MODEST WARMING TREND MONDAY INTO TUESDAY. THERE IS
MUCH LOWER CONFIDENCE IN THE EVOLUTION OF THE LARGE-SCALE
PATTERN BY THE MIDDLE OF NEXT WEEK, BUT THERE ARE LOW CHANCES
FOR ANOTHER TROUGH TO BRING ADDITIONAL RAIN. -36
AVIATION...THROUGH 12Z THURSDAY
BROAD HIGH PRESSURE WILL
MAINTAIN SIMILAR CONDITIONS TO RECENT DAYS, HOWEVER WEAK
OFFSHORE FLOW WILL ACT TO LESSEN THE CHANCES FOR FOG AND LOW
STRATUS COMPARED TO MORNINGS EARLIER THIS WEEK. WITH LARGELY
CLEAR SKIES SUPPORTING EFFICIENT RADIATIVE COOLING, TERMINAL
OBSERVATIONS ACROSS THE REGION ALREADY SHOW RELATIVE HUMIDITY OF
90% OR GREATER, MEANING ANY FURTHER COOLING MAY SUPPORT
FOG/MIST DEVELOPMENT. LATEST SATELLITE IMAGERY DEPICTS PATCHY
COVERAGE OF LOW CLOUDS ALONG THE COAST, BUT RECENT TRENDS SEEM
TO FAVOR IFR VIS/CIGS FROM FOG OR MARINE STRATUS UNTIL AFTER
SUNRISE, WHILE TEMPO GROUPS THROUGH 16Z WED INDICATE CONDITIONS
WILL LIKELY CONTINUE TO FLUCTUATE. INLAND, CHANCES FOR IFR
VIS/CIGS ARE MUCH LOWER, 15-20% OR LESS, BUT PERIODS OF MVFR VIS
FROM MIST MAY OCCUR AT FAVORED SITES, MOST LIKELY IN THE
SOUTHERN WILLAMETTE VALLEY BUT ALSO CENTRAL WILLAMETTE VALLEY
AND CASCADE FOOTHILLS SITES.
ANY RESTRICTED VIS/CIGS WILL TEND TO IMPROVE TO VFR BY 16-17Z
WED AS DAYTIME HEATING AND DIURNAL WINDS ENCOURAGE VERTICAL
MIXING. LIGHT OFFSHORE FLOW EARLY THIS MORNING WILL BUILD OUT OF
THE NORTH TO NORTHWEST TO 10-15 KT WITH GUSTS AROUND 20 KT
ALONG THE COAST, AND TO 5-10 KT INLAND BY THIS AFTERNOON.
KPDX AND APPROACHES...VFR CONDITIONS BENEATH CLEAR SKIES FAVORED
THROUGHOUT THE PERIOD. LOW CHANCES, AROUND 20%, FOR MVFR OR
WORSE VIS/CIGS FROM 14-17Z WED IF FOG/MIST OR LOW STRATUS IS
ABLE TO DEVELOP. HIGH CONFIDENCE IN A RETURN TO VFR CONDITIONS
AFTER 16-17Z WED. DIURNAL NORTHWEST WINDS RISE TO AROUND 5 KT
THIS AFTERNOON, THEN EASE THIS EVENING. -36
MARINE
HIGH PRESSURE OFFSHORE WILL CONTINUE TO MAINTAIN
DIURNAL NORTHERLY WINDS THROUGH THE WEEK WITH PEAK AFTERNOON AND
EVENING WIND GUSTS OF 20-25 KT TODAY THROUGH THURSDAY. SMALL
CRAFT ADVISORIES REMAIN IN EFFECT ACROSS THE WATERS FROM 1 PM
PDT TODAY THROUGH THIS EVENING, WITH ADDITIONAL ADVISORIES
LIKELY ON THURSDAY. EXPECT LARGELY WIND-DRIVEN SEAS AROUND 4-6
FT WITH A WEST-NORTHWEST SWELL OF 3-4 FT AT 10-12 SECONDS. HIGH
PRESSURE ALOFT WILL ALSO SUPPORT AREAS OF DENSE FOG DEVELOPING
NIGHTLY THROUGH THE MORNING HOURS AS CLOUD BASES ARE COMPRESSED
DOWN TO THE SURFACE.
MORE ACTIVE MARINE CONDITIONS ARE LIKELY IN THE LATTER HALF OF
THE WEEK AS TROUGHING OVER THE GULF OF ALASKA GENERATES A
BUILDING NORTHWEST SWELL. SEAS WILL INCREASE TO 7-10 FT
WEDNESDAY INTO THURSDAY, WITH THE LONGER-PERIOD SWELL ALSO
SUPPORTING A MODERATE RISK FOR SNEAKER WAVES AT THE COAST. WINDS
OUT OF THE NORTHWEST ASSOCIATED WITH A COLD FRONT WILL INCREASE
ON FRIDAY AS SEAS PEAK AT 8-12 FT BY FRIDAY NIGHT, BEFORE WINDS
EASE AND VEER OUT OF THE NORTH WHILE SEAS FALL BACK TO 5-7 FT
FROM SATURDAY INTO EARLY NEXT WEEK. -36/03
CLIMATE
DAILY RECORD HIGH TEMPERATURES FOR OCTOBER 8
LOCATIONVALUE (YEAR)
ASTORIA 81 (1951, 1971)
PORTLAND INT'L87 (2022)
VANCOUVER, WA89 (1891)
HILLSBORO89 (2022)
MCMINNVILLE88 (2022)
SALEM84 (1971, 2022)
EUGENE83 (1934, 1943)
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 2 AM PDT
THURSDAY FOR PZZ210-251>253.
SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 5 AM PDT
THURSDAY FOR PZZ271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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